forked from src-d/go-mysql-server
/
util.go
154 lines (125 loc) · 2.43 KB
/
util.go
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package parse
import (
"bufio"
"bytes"
"fmt"
"io"
"io/ioutil"
"strings"
"unicode"
errors "gopkg.in/src-d/go-errors.v1"
)
var (
errUnexpectedSyntax = errors.NewKind("expecting %q but got %q instead")
errInvalidIndexExpression = errors.NewKind("invalid expression to index: %s")
)
type parseFunc func(*bufio.Reader) error
func expectRune(expected rune) parseFunc {
return func(rd *bufio.Reader) error {
r, _, err := rd.ReadRune()
if err != nil {
return err
}
if r != expected {
return errUnexpectedSyntax.New(expected, string(r))
}
return nil
}
}
func expect(expected string) parseFunc {
return func(r *bufio.Reader) error {
var ident string
if err := readIdent(&ident)(r); err != nil {
return err
}
if ident == expected {
return nil
}
return errUnexpectedSyntax.New(expected, ident)
}
}
func skipSpaces(r *bufio.Reader) error {
for {
ru, _, err := r.ReadRune()
if err == io.EOF {
return nil
}
if err != nil {
return err
}
if !unicode.IsSpace(ru) {
return r.UnreadRune()
}
}
}
func checkEOF(rd *bufio.Reader) error {
r, _, err := rd.ReadRune()
if err == io.EOF {
return nil
}
return errUnexpectedSyntax.New("EOF", r)
}
func optional(steps ...parseFunc) parseFunc {
return func(rd *bufio.Reader) error {
for _, step := range steps {
err := step(rd)
if err == io.EOF || errUnexpectedSyntax.Is(err) {
return nil
}
if err != nil {
return err
}
}
return nil
}
}
func readIdent(ident *string) parseFunc {
return func(r *bufio.Reader) error {
var buf bytes.Buffer
for {
ru, _, err := r.ReadRune()
if err == io.EOF {
break
}
if err != nil {
return err
}
if !unicode.IsLetter(ru) && ru != '_' {
if err := r.UnreadRune(); err != nil {
return err
}
break
}
buf.WriteRune(ru)
}
*ident = strings.ToLower(buf.String())
return nil
}
}
func oneOf(options ...string) parseFunc {
return func(r *bufio.Reader) error {
var ident string
if err := readIdent(&ident)(r); err != nil {
return err
}
for _, opt := range options {
if strings.ToLower(opt) == ident {
return nil
}
}
return errUnexpectedSyntax.New(
fmt.Sprintf("one of: %s", strings.Join(options, ", ")),
ident,
)
}
}
func readRemaining(val *string) parseFunc {
return func(r *bufio.Reader) error {
bytes, err := ioutil.ReadAll(r)
if err != nil {
return err
}
*val = string(bytes)
return nil
}
}